Synchronization Techniques

Synchronous send and receive: if receive is expecting more data than was sent, it can block, which can then lead to deadlock.
Asynchronous send and synchronous receive: good if sender does not care about reception.
Synchronous send and asynchronous receive: the receive can be implemented in various ways
1. Receive returns immediately with either data or null.
2. Receipt triggers a call-back.
Asynchronous send and receive: requires the IPC to implement a queue.
Even under synchronous we don't wait forever. There is often a timeout.